Plaster board



Dec. 16, 1924. 1,519,180

C. E. WILLIAMS PLASTER BOARD Filed Aug. 18, 1922 1;? 7/6 21 for: P fiiqreizce Zia? 72502115,

Patented Dec. 16, 1924.

- UNITED STATES PATENT OFFICE.

CLARENCE E. WILLIAMS, OF CHICAGO, ILLINOIS, ASSIGNOR '10 BEAVER PRODUCTS CO., INC, OF BUFFALO, NEW YORK, A CORPORATION OF NEW YORK.

PLASTER BOARD.

Application filed August 18, 1922. Serial No. 582,605.

To all whom it may com-cm.

Be it known that I, CLARENCE E. WIL- LIAMS, a citizen of the United States, and a resident of the city of Chicago,county of Cook, State of Illinois, have invented an Improvement in Plaster Board, of which the following is a specification.

This invention relates to composite building board, such as plaster board or the like, and to the method of making it.

Among other objects, the inventionis intended to provide a plaster board having an improved protected edge which shall be of neat appearance, secure and durable.

The invention consists in the novel'constructions, combinations and methods, hereinafter described or claimed, for carrying out the above stated objects and such other objects as will hereinafter appear.

The invention may be more readily under stood by reference to one illustrative method and construction embodying the invention and shown in the accompanying drawing.

In said drawing:

Fig. 1 illustrates a perspective view of a.

" portion of a plaster board having a protected edge embodying this invention.

Fig. 2 is a cross section transversely of the board-illustrating the same at one stage of manufacture before ,the margins of the cover sheets have been folded over the edges of the plaster body. Fig. 3 is a cross section of the board along the lines 83 of Fig. 1 showing the illustrative protected edge in fiQs-hed form.

The invention-is illustrated asapplied to a double-face plaster board, that is, aboard either side of which may be employed'as the face side of the board. In the drawing 10 and 11 designate cover sheets which may be termed, for convenience, top and bottom cover sheets, respectively. Such cover sheets are preferably of fibrous material of the proper weight and quality, such as paper. Between the cover sheets is a .body 12of plaster or the like to which the cover sheets preferably adhere from edge to edge of the plaster body. This adhesion of the cover sheets to the plaster body reinforces the space 16 between-the margins falls approximately at the middle of the ,edge of the board. The margins are cemented in place preferably by the adhesive character of the plaster itself;

To improve the adhesion of the folded margins to the plaster body and to render the same less likely to unfold, these margins are treated in a suitable manner to render them more pliable and less likely to unfold and pull loose from the plaster. Heretofore the inherent stiffness and resilience of the paper cover sheets, particularly when the edges of the cover sheets fall at the edges of the board, has caused the folded margins to pull loose from the plaster before the same had been firmly cemented in place by the setting of the plaster. In the form illustrated the margins 13 and 14 are thinned,

scarfed or beveled, as at 17, thus, weak-- ening the margins and rendering them more pliable. Preferably, this scarfing or beveling commences at a point 18 somewhat back of the intended corner of the board. The margins so, beveled fold more easily at the corners of the board and adhere more readily to the plaster body. Heretofore at the corners of the board the stiffness of the paper has tended to cause the same to pull away from the plaster during the initial stages of manufacture, while 'the plaster was in plastic condition. 'When the marginshave been weakened, they conform more readily to the body of plaster and adhere theretountil the same has set.

The beveling or feathering of the margins 14 and 15 somewhat mutilates the same or at least exposes or loosens the fibres of the paper so that the same may become more intimately bonded with the body of plaster. The margins may be beveled to any degree thought necessary to produce the desired effect, namely to cause the margins to remain in folded relation in contact with the plaster until the samehas set sufficiently.

The margins of the cover sheets need not necessarily be scored along the corners, of the board to cause the same to fold readily. The scarfing of these margins back of the corners of the board obviates this.

Plaster board of this character may be manufactured in any suitable manner. If what is termed as the continuous process be employed, plaster is placed in suitable quantities upon a traveling cover sheet,

- called the bottom sheet. In the-illustrative I form the sheet 11 is employed. as the bottom sheet. The top cover sheet 10 is then.

applled-and, preferably simultaneously, the

present as This pressure may be plaster 1s spread to an even depth across the board. At some stage in the manufacture of the board, the :margins 13 and 14 are folded over the edge of the plaster body. In the preferred method the lower margins 14 are folded up into position before the top cover. sheet is applied and before thefrom the application of the plaster, the

margins 13 and 14: are scarfed or beveled. This may be accomplished by rapidly rotating emery wheels or other grinding devices, the surfaces of which are set at the proper angle to the surface of the sheet to produce the desired result. In the illustrative form this bevel'is produced on the inner surfaces of the margins. This preserves the surface finish of the outer surface of the margins. However, if desired, the bevel may occur on the outer surface of the'margins.

Pressure is applied to the edges of the board while the plaster is still inplastic condition, to cement the folded margins firmly in place, bond between fibres on the beveled margins. and with whatever mutilation of the margins may be a result of the 'scarfing operation. removed when the plaster, with the cooperation of the cover sheets, is sufficiently set to retain its proper shape,'particular'ly at the edges.

Obviously, the construction, conformation or shape of the edges of the board may be varied considerably according to requiremerits. For example, one or both faces of the board may be beveled near the edges toprovide an enlarged area for receiving plaster intendedto cover the joints of the adjacent boards when the same are placed After the topsheethas been nation, a

and to produce a mechanical the plaster and the loosened nation, a

in a wall. Furthermore, the edges of the board need not be plane surfaced and at right angles to the faces of-the board, but

may be concave or formed to any other desirable contour.-

Obviously, the inventionis not limited to any particular construction and the details of the illustrative board and 'method of making it may. be variously modified.

'Moreover, 1t is not indispensable that all features of the invention be used conjointly, as certain features may be employed to advantage -in various different combinations and sub-combinations.

Having thus described my invention, I

claim:

1. A plaster .board comprising, in combination, a body of plaster or the like, covering sheets disposed over the respective faces of said body, the margins of said cover sheets being folded over the edges of said body in non-overlapping relation, and certain of said margins being weakened to re duce the stiffness of the material thereof.

2'. A plaster board comprising, in comb1-.

nation, a body of plaster or the like, cover sheets covering the opposite faces of said body from edge to edge, the margins of said cover sheets being folded over and cemented to the edges of said body without overlapping, certain. of said margins being reduced in thickness.

body and adhering thereto to reinforce said 3. A plaster board comprising, in combi- I nation, a body ofplaster or the like, cover sheets covering the opposite facs of sald body and adhering thereto to reinforce said body from edge to edge, the margins of said cover sheets certain of said'margins being reduced in thickness fora distancebeyon the corners of said body.

4. A plaster board comprising,in comb1-' body of plaster or the like, cover sheets covering the opposite faces of said body and adhering thereto to reinforce said body from edge to edge, the margins of said cover sheets being folded over and cemented .to' the edges of said'body without overlapping, certain of said margins being tapered whereby the same remain. more readily in folded relation. 1

5. A plaster board comprising, in combination, a body of plaster or the like, cover sheets covering the opposite faces of said body and adhering thereto to reinforce said body from edge to edge, the margins of each of said cover sheets being tapered, and folded over the edges of said body and cemented thereto.

6. A plaster board comprising,- in combisheets covering the opposite faces of said body and adhering thereto to reinforce sald being folded over and cemented to the edges of said body without.

overlapping,

body of plaster flor' the like, cover body from edge to edge, the margins of each of said cover sheets being tapered and folded over the edges of said body and cemented thereto without overlapping.

7. A plaster board comprising, in combination, a body of plaster or the like, cover sheets covering the opposite faces of said body and adhering thereto to reinforce said body from edge to edge, the margins of each of said cover sheets being tapered for a distance back of the corners of said body and. folded over the edges thereof and oemented thereto.

8. A plaster board comprising, in combination, a body of plaster or the like, cover sheets disposed over the respective faces of said body and having margins thereof reduced in thickness for a distance back of the corners of said body to render said margins more pliable, said margins being folded over to cover the edges of said body, and cemented thereto.

9. A plaster board comprising, in combination, a body of plaster or the like, cover sheets disposed over the respective faces of said body and having margins thereof reduced in thickness for a distance back of the corners of said body to render said margins more pliable, said margins being folded over to cover the edges of said body, to meet substantially along the middle thereof without overlapping, and being cemented thereto.

10. The method of making plaster board which comprises applying cover sheets to the opposite faces of a body of plaster or the like, treating said cover sheet margins to render them more pliable, folding the same over the edge of said bodywithout overlapping and cementing the same thereto.

11. The method of making plaster board which comprises applying cover sheets to the opposite faces of a body of plaster or the like, reducing the thickness of said cover sheet margins to render the same more pliable, folding said margins to cover the edges of said body and cementing the same thereto.

12. The method of making plaster board which comprises applying cover sheets to the opposite faces of a body of plaster or the like, reducing the thickness of said cover sheet margins from a point beyond the corners of the edge-of said body to render the same more pliable, folding said margins to cover the edges of said body and cementing the same thereto.

13. The method of making plaster board which comprises applying cover sheets to the opposite faces of a body of plaster or the like, tapering said cover sheet margins to render the same more pliable, folding said margins to cover the edges of said body without overlapping and cementing the same thereto.

14:. The method of making plaster board which comprises applying cover sheets to the opposite faces of a body of plaster or the like, grinding the margins of said cover sheets so as to render the same more pliable, folding said margins to cover the edges of said body without overlapping and cementing the same thereto.

In testimony whereof, I have signed my name to this specification.

CLARENCE E. WILLIAMS. 

